Spirally wound paper tube



SPIRALLY WOUND PAPER TUBE Sheet of Filed NOV. 3U. 1966 L7 ais/vf Jan. 14, 1969 y B, R W||A1 EY ET Al. 3,421,550

SPIRALLY WOUND PAPER TUBE Sheet 2 of 2 Filed NOV. 3G. 1966 United States Patent O 4 Claims This invention relates to tubular articles and their component parts and more particularly to a multi-ply, spirally wound tube composed of brous material such as paper `which is readily subject to dimensional change under varying moisture conditions.

In the construction of paper tubes and in particular spirally wound multi-ply paper tubes, it is frequently desirable that such tubes be provided with a layer or ply of vapor barrier material within the wall of the tube to combat the tendency of the tube to follow the moisture conditions to which it is subjected and thereby impart dimensional stability to the tube. As is well known, when such a tube undergoes a change in its moisture content resulting from exposure to differing moisture conditions, considerable dimensional change in the tube will generally occur so that a tube manufactured for a particular t will become useless and must be discarded with attendant loss, unless costly steps are taken to return such tubes to their original manufactured size.

While ambient moisture conditions are a frequent contributor to dimensional change in paper tubes manufactored under differing moisture conditions, other factors often contribute to a change in the moisture content of the tubes. For instance, a surface of a tube such as its outer surface may be exposed to excessive moisture such as when a wet sheet material is wound on the tube and the moisture in the sheet material is transmitted to the tube.

In order to reduce or eliminate the change in moisture content of such paper tubes, it has been proposed to pro' vide a paper strip used in the winding of the tube with a coating of a suitable vapor barrier material such as polyethylene or the like and then spirally wind this strip in overlapping relationship to provide a barrier ply within the tube wall. While such a technique provides a vapor barrier throughout most of the tube wall, a thickness of paper remains along the spiral seam between the overlying edges of the barrier material through which moisture can pass. Furthermore, a spiral ridge is formed as a result of these overlapping edges producing a highly undesirable distortion in the tube wall along the spiral seam. If a butt joint is employed between the edges of adjacent convolutions in the spirally wound strip, a spiral crack remains in the barrier material through which moisture can pass.

It has been proposed to form a barrier strip for a spirally wound tube by applying a layer of barrier material to a paper back-up strip with the barrier material overhanging the paper back-up strip along one edge. |Even if a thick self-supporting layer of barrier material is employed with the attendant high costs, the fragile nature of this barrier material overhang results in the need for special handling and special cutting which at best does not eliminate frequent damage to the overhang. Furthermore, special adhesives are generally required to adhere the layer of barrier material to the adjacent wound paper ply in the tube in order to prevent slippage between the plies.

Accordingly, a primary object of this invention is to provide a new and novel composite barrier strip for forming a vapor barrier within the wall of spirally wound paper tubes.

3,421,550 Patented Jan. 14, 1969 Pice Another object of this invention is to provide a new and novel composite barrier strip for forming a vapor barrier in spirally wound paper tubes which eliminates both the spiral crack common to a butt joint as well as the spiral ridge of an overlapped spiral seam through which vapor can pass.

A further object of this invention is to provide a new and novel composite barrier strip for forming a vapor barrier in spirally wound paper tubes which prevents the passage of vapor through the tube wall, which uses a minimum of vapor barrier material, which permits the use of present day tube winding apparatus without special handling and which produces a tube of high dimensional stability so as to eliminate the high manufacturing costs heretofore incurred in tube loss resulting from changes in tube size with changes in tube moisture content.

Other objects and advantages of the invention will become apparent from the following description taken in connection with the accompanying drawings.

The objects stated above and other related objects in this invention are accomplished by providing a tri-ply laminated composite strip which comprises a top and bottom paper ply arranged in overlying, transversely staggered relationship. An inner ply of vapor barrier material such as polyethylene or the like is sandwiched between the top and bottom paper plies in adherence therewith and this vapor barrier material inner ply extends transversely from the extended side edge of the top ply to the extended side edge of the bottom ply to form oppositely facing ledges of barrier material along opposite side edges of the tri-ply strip. This tri-ply composite strip is most suitable for use in a multi-ply spiral ly wound tube to form a barrier ply. When spirally wound into such a tube together with conventional paper plies, the adjacent convolutions of the tri-ply strip are overlapped with the ledges of barrier material of adjacent convolutions arranged in overlapping relationship and with the edges of adjacent convolutions of the top and bottom paper plies of the tri-ply strip in abutting relationship whereby the barrier strip forms a vapor irnpermeable barrier ply in the tube wall.

The novel features which are believed to be characteristic of the invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation may be best understood by reference to the following description taken in conjunction with the accompanying drawings in which:

FIGURE 1 is a diagrammatic view illustrating the formation of the tri-ply composite strip of the invention;

FIGURE 2 is an enlarged view taken in the direction of the arrow 2 of IFIGURE l illustrating a portion of the apparatus;

FIGURE 3 is an enlarged sectional View of the material processed by the apparatus of FIGURE 2 with lines of severance indicated by dash-dot lines.

FIGURE 4 is a View similar to FIGURE 2, but illustrating a modification of the apparatus of the invention;

FIGURE 5 is an enlarged broken away sectional view of the barrier strip of the invention;

FIGURE 6 is an isometric View of a spirally wound tube incorporating the barrier strip to FIGURE 4;

FIGURE 7 is an enlarged sectional view of the portion of the tube of FIGURE 6 within the dotted lines;

FIGURE 8 is a view similar to FIGURE 7 showing another form of a spiral tube wall incorporating the barrier strip of the invention.

FIGURE 9 is an enlarged sectional view taken substantially along line 9-9 of FIGURE 6 in the direction of the arrows; and

FIGURE 10 is a sectional view of a portion of the tube wall shown in FIGURE 9.

Referring now to the drawings, there is shown diagrammatically in FIGURE l an apparatus for practicing the novel method of the invention by means of which the novel tri-ply composite barrier strip, identified generally in FIGURE by the numeral 11, is produced. In the apparatus shown in FIGURE 1, a strip of paper 12 is supplied from a supply roll .13 and advanced in the direction of the arrow I over guide rollers 14.

At the same time, a pair of paper strips, identified in FIGURES 2, 3 by the numerals 17, 18, are also supplied from a source such as a common supply roll 19 and advanced in the direction of the arrow P over guide rollers 21. As shown in FIGURES 2, 3 these paper strips 17, 18 which may be different widths if desired are preferably of substantially the same width and are arranged in laterally spaced relationship to form a clearance space 22.

The paper strip 12 and the pair of paper strips 17, 18 are brought together in overlying relationship on the surface of a drum 23 with the paper strip 12 adjacent the drum surface. The drum 23, which is cooled internally by any suitable means such as circulating water, is positively driven in any conventional manner (not shown). As shown best in FIGURE 3, the width of the paper strips 12, .17, 18 is selected so that in the relationship shown, the outer side edges of the strips 17, 18 project laterally outward a short distance from the outer side edges of the overlying paper strip 12.

Referring again to FIGURE 1, at the nip of the paper strips 12, 17, 18, a relatively thin film 24 of vapor barrier material such as polyethylene is extruded from any conventional plastic extrusion unit 26 which incorporates suit-able heating means, designated generally by the numeral 27, for reducing the plastic material or polyethylene toa molten state in the well-known manner. It has been found in practice that a polyethylene film 24 having a thickness within the range of approximately 0.0005 to 0.004 inch produces the desired results of the invention. Preferably a ilm having a thickness of approximately 0.002 inch is employed. The thickness of the paper strips 12, 17, 18 may be within the range of approximately 0.01 to 0.05 inch and preferably the paper strip thickness is approximately 0.015 inch.

Upon contact with the overlying surfaces of the paper strips 12, 17, 18, the hot extruded polyethylene ilm 24 fuses to the paper to form a tri-ply laminated composite structure such as is shown in FIGURES 2, 3 and which is designated generally by the numeral 28. It will be noted that the extruded polyethylene lm 24 extends transversely between the extruded side edges of the paper strips 17, 18.

The tri-ply structure 28 is then advanced over the surface of the drum 23 in the direction lof the arrow T and travels over glide roller 29 to a group of spaced cutting devices such as trimming knives 31 suitably supported for free rotation on a shaft 32. Each of the trimming knives 31 has associated therewith a back-up wheel 33 supported for free rotation on a shaft 34 in a position such that the cutting edge of each of the trimming knives 31 extends slightly below the periphery of its associated wheel 33 to provide a shearing type cutting action on the structure 28.

The trimming knives 31 are spaced as shown in FIG- URE 2, so that the center knife 31 severs the paper strip 12 and polyethylene film 24 centrally which line of cut is coincident with the center line of the clearance space 22. The outer knives 31 serve to trim end portions 35 from the polyethylene film 24 and paper strips 17, 18 so that the tri-ply structure 28 formed in the apparatus of FIGURE 1 is now separated into a pair of tri-ply laminated composite barrier strips 11. This pair of barrier strips 11 is subsequently wound onto suitable take-up means such as a take-up roll 36 positively driven in any well-known manner (not shown).

As shown best in FIGURE 5, each tri-ply barrier strip 11 therefore comprises a bottom paper ply 41, a top paper ply 42 of substantially the same width in overlying, transversely staggered relationship therewith and an inner ply 43 of vapor barrier material such as polyethylene extending transversely from the extended side edge of the top ply 42 to the extended side edge of the bottom ply 41 to form oppositely facing ledges 44, 46 of barrier material along opposite sides of the strip 11.

The barrier strip 11 lends itself readily for use as a ply in a multi-ply spirally wound tube such as is identified in FIGURE 6 by the numeral 47. As is well known, such a tube 47 is formed by spirally winding a plurality of plies of paper in overlying relationship with adhesive therebetween so that a spiral seam 48 is usually discernible on the surface of the tube. As has been previously explained, such paper tubes are readily susceptible to dimensional change with change in the moisture content of the paper Of which the tube is composed when it is exposed of differing external moisture conditions. By use of the barrier strip 11 of the invention, the effect of external moisture conditions on the tube can be virtually eliminated.

Any number of barrier strips 11 may be employed in the spiral tube 47 and the position of the barrier strip 11 in the tube wall may be selected in accordance with the end result desired. For instance, where it is desired t0 seal the tube wall from external moisture or vapor, a barrier strip is wound adjacent the inner and outer surface of the tube 47 as shown in FIGURES 7, 9 with the intermediate spirally wound paper plies 49 therebetween. An innermost spirally wound paper ply 50 is preferably also employed to facilitate the winding operation.

In the winding of the tube 47 employing the barrier strips 11, conventional winding apparatus is used and both the barrier strips 11 and paper plies 49, 50' are fed to the winding apparatus in the conventional manner. As shown in FIGURES 9, 10, the barrier strip 11 is wound with the side edges of adjacent convolutions in overlapping relationship so that the ledges of barrier material 44, 46 overlap as shown and the side edges `of adjacent convolutions of the top and bottom paper plies are positioned in abutting relationship. Thus a continuous vapor impermeable barrier within the tube wall is formed not only in the area in which the inner plastic ply 43 is secured to the paper plies 41, 42 but also throughout the overlapping portions of the inner barrier material ply 43 formed by the ledges 44, 46 which form a seal between adjacent convolutions of the barrier strip 11.

It has been found that the tightly compressed engagement between the overlapping barrier material ledges 44, 46 produce a tight seal therebetween so that an adhesive at this point for sealing these surfaces is generally not necessary. However, if desired, an adhesive could be used or a heat sealing technique for the barrier material can be employed if suitable. By bonding together the overlapping barrier material, a greatly improved Water barrier is obtained.

In the tube structure of FIGURES 7, 9, vapor is thereby prevented from entering the tube through the outer surface of the tube and through the inner surface of the tube due to the two layers of barrier material included in each of the wound barrier strips 11.

In some cases, it is desirable to provide a tube which will not admit moisture or vapor through its outer surface only such as when the tube is wound with a wet web of film, paper or the like. As shown in FIGURE 8, only a single barrier strip 11 is employed in such a tube together with inner paper plies 49 and although moisture can enter the tube through its inner surface, the outer surface of the tube is provided with acontinuous vapor barrier formed by the overlapped layer of barrier material 43.

The novel construction of the barrier strip 11 of the invention lends itself to production of a relatively large number of such barrier strips simultaneously. Referring now to FIGURE 4, this feature is illustrated by a tri-ply structure formed with apparatus generally similar to that shown in FIGURE l and which structure is identified generally by the numeral 51. It should be understood that this tri-ply structure 51 may be of any width desired depending on the capacity of the equipment employed.

The structure 51 includes a plurality of laterally spaced paper strips 52 and a plurality of similarly spaced paper strips 53 arranged in overlying, transversely staggered relationship with a continuous layer 54 of vapor barrier material therebetween as described above. The spaced strips 52, 53 thereby form clearance spaces 54, 55 respectively.

As in Athe apparatus shown in FIGURE 2, a plurality of banks of laterally spaced trimming knives 31 and backup Wheels 33 are employed mounted on shafts 32, 34 respectively and the knives 31 are positioned to vertically sever the tri-ply structure 51 centrally of the clearance spaces 55, 56 between the paper strips 52, 53 to form a plurality of barrier strips 11.

With the novel construction and method of this invention, there has been provided a product highly useful in spirally wound multi-ply paper tube construction which can be incorporated within the tube using commonly employed apparatus and techniques and which provides a highly effective vapor barrier at any desired location within the tube wall. No sacrifice need be made in tube strength as a result of the incorporation of this barrier strip and there is no change in the appearance of the tube such as an unsightly spiral ridge or the like. The barrier strip manufactured in accordance with the invention utilizes inexpensive, readily available materials and may be produced using a simple easily operated device with a number of such barrier strips being produced simultaneously limited only by the capacity of the equipment. Furthermore, the barrier strips may be formed using relatively thin vapor barrier lm with the attendant reduced costs and without the problems incident to the handling of such thin films as encountered in previously proposed strip constructions.

While an extrusion laminated film is the desired form of the invention, the barrier strip is readily adaptable to formation with the use of a ilow coating or knife coating of the film or in particular an adhesive lamination of the film between the paper strips. In addition, while polyethylene has been specified as a suitable vapor barrier material for use in the invention, any desired type of vapor barrier material may be employed such as wax, asphalt, polyvinyl chloride and other resins. Furthermore, if desired, the ledges of vapor barrier material formed on the barrier strip of the invention may be provided with interlocking surfaces so as to increase the sealing action of the overlapping barrier material ledges in the wound tube.

While there has been described what at present is considered to be the preferred embodiment of the invention, it will be understood by those skilled in the art that various changes and modilications may be made therein without departing from the invention and, therefore, it is the aim of the appended claims to cover all such changes and modications as fall within the true spirit and scope of the invention.

Having thus described the invention, what is claimed 1. A spirally wound paper tube including a ply formed by a tri-ply laminated strip, said strip comprising the combination of a top and bottom paper ply of substantially the same width, said top ply being arranged in transversely staggered overlying relationship with said bottom ply, an inner ply of vapor barrier material sandwiched between said top and bottom paper plies and secured thereto, said inner ply of vapor barrier material extending transversely from the outer side edge of said top ply to the outer side edge of said bottom ply to form oppositely facing ledges of barrier material of substantially the same width along opposite sides of said tri-ply strip, said tri-ply strip being spirally wound with the ledges of barrier material of adjacent convolutions in overlapping relationship and with the edges of adjacent convolutions of said top and bottom paper plies in abutting relationship.

2. A spirally Wound paper tube in accordance with claim 1 including a plurality of spirally wound paper plies and wherein said spir-ally wound tri-ply laminated strip is adhesively secured to at least one of said paper plies to form a barrier ply adjacent one surface of said tube.

3. A spirally wound paper tube in accordance with claim 2 including a pair of said tri-ply strips, one of said tri-ply strips positioned adjacent the outer surface of said tube and the other of said tri-ply strips positioned adjacent the inner surface of said tubes.

4. A spirally wound paper tube in accordance with claim 1 wherein said inner ply of vapor b-arrier material is formed from polyethylene and is fusedly secured to said top and bottom paper plies to form said tri-ply laminated strip whereby said oppositely facing ledges are formed of polyethylene.

References Cited UNITED STATES PATENTS 2,035,304 3/1936 Diifenbach 138--144 3,126,034 3/1964 Kennedy 138-144 3,338,270 8/1967 Denenberg 13S-144 PATRICK D. LAWSON, Primary Examiner. 

1. A SPIRALLY WOUND PAPER TUBE INCLUDING A PLY FORMED BY A TRI-PLY LAMINATED STRIP, AND STRIP COMPRISING THE COMBINATION OF A TOP AND BOTTOM PAPER PLY OF SUBSTANTIALLY THE SAME WIDTH, SAID TOP PLY BEING ARRANGED IN TRANSVERSELY STAGGERED OVERLYING RELATIONSHIP WITH SAID BOTTOM PLY, AN INNER PLY OF VAPOR BARRIER MATERIAL SANDWICHED BETWEEN SAID TOP AND BOTTOM PAPER PLIES AND SECURED THERETO, SAID INNER PLY OF VAPOR BARRIER MATERIAL EXTENDING TRANSVERSELY FROM THE OUTER SIDE EDGE OF SAID TOP PLY TO THE OUTER SIDE EDGE OF SAID BOTTOM PLY TO FORM OPPOSITELY FACING LEDGES OF BARRIER MATERIAL OF SUBSTANTIALLY THE SAME WIDTH ALONG OPPOSITE SIDES OF SAID TRI-PLY STRIP, SAID TRI-PLY STRIP BEING SPIRALLY WOUND WITH THE LEDGES OF BARRIER MATERIAL OF ADJACENT CONVOLUTIONS IN OVERLAPPING RELATIONSHIP AND WITH THE EDGES OF ADJACENT CONVOLUTIONS OF SAID TOP AND BOTTOM PAPER PILES IN ABUTTING RELATIONSHIP. 